To suppress a torque change caused by fluctuation of an electrical angle between control periods.

For PWM conrolling an inverter 3, a motor electrical angle advancing between control periods is estimated relating to a motor electrical angle θ taken in each sampling period dt, a torque change value during this time is estimated, a voltage command value Vu**, Vv**, Vw** with its means value conformed to a torque command value is used, to control the inverter. In this way, a deviation between the torque command value and the actual torque mean value is negated, thereby eliminating a torque change between the control periods.